Avalanche Forecast

Issued: Dec 18th, 2015 3:00PM

The alpine rating is considerable, the treeline rating is moderate, and the below treeline rating is moderate. Known problems include Wind Slabs and Persistent Slabs.

esharp, Avalanche Canada

Cariboos.

The new snow may be hiding pockets of old wind slab on south aspects with fresh soft slabs developing in east facing lee features through the day.

Summary

Confidence

Moderate - Wind effect is extremely variable

Weather Forecast

SATURDAY: flurries, moderate westerly winds, a warming trend with a high of -5C at treeline. SUNDAY: light snow with accumulations of up to 7cm by the end of the day, moderate southerly winds, -5C at treeline. MONDAY: flurries, light southerly winds, temperatures are forecast to fall to -10C at treeline through the day.

Avalanche Summary

Avalanche professionals in the field are reporting sluffing in extreme terrain, and small soft slabs in the immediate lee of wind loaded features are reactive to skier traffic.

Snowpack Summary

New snow 15cm of new snow on Friday, combined with moderate southwest winds have formed fresh soft slabs in lee features in the alpine and at tree-line. Between 80 and 150cm of snow now sits on an extensive persistent week layer. The form of this layer varies depending on aspect and elevation: it can be found as a crust on south facing slopes in the alpine, or as large grained surface hoar and facets below tree-line. The surface hoar is most widespread in an elevation band between 1400m and 1800m. Snow pit tests suggest that human triggering of this interface is still possible, although unlikely, and that if it does fail the overlying slab is stiff enough to propagate the failure over a large distance. Below this the snowpack is thought to be mainly well settled.

Problems

Wind Slabs

Variable winds and an abundance of low density snow available for transport will continue to produce wind slabs in lee features. Look for shooting cracks as a sign you entering wind a wind loaded feature.

Avoid freshly wind loaded features at ridge-line and use ridges or ribs to sneak around these problem areas.>The recent snow may now be hiding windslabs that were easily visible before the snow fell.>

Aspects: North, North East, East, South East, South, South West.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 4

Persistent Slabs

A layer of buried surface hoar can be found between 1400m and 1800m. Watch out for signs of instability like wumphing to guide you through this elevation band.

Avoid open slopes, convex rolls, burns, cutblocks and terrain traps when traveling below treeline. This is where buried surface hoar is best preserved and most volatile.>

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

2 - 4

Valid until: Dec 19th, 2015 2:00PM